Displays have been incorporated to electronic devices to improve the usability of the devices. For example, presently ordinary mobile stations incorporate a display device, on which the user can monitor the success of keying in a telephone number and by using which he/she can edit the telephone number being keyed in. In tune with the evolution of mobile stations they have been used for communicating by short messages and in future mobile station also by transferring moving images. For these uses it would be preferable for the display of a mobile station to be large so that it would be easy to recognise textual information and/or images. The size of new mobile stations has been perpetually decreasing to improve portability while the evolution of their battery technology and energy maintenance has enabled a stretching of their stand-times even to weeks. With the future mobile station models the need for large amounts of processing required by manipulation of moving images along with an increase in display size and furthermore the transition from passive matrix displays to colour active matrix displays of better quality will significantly increase the power consumption of mobile stations and decrease their standby-time.
The power consumption of the liquid crystal displays now used in mobile stations, as well as that of emission displays being designed, increases relatively to their size. Thus a larger display needed to provide a larger picture area unavoidably consumes more energy and shortens the stand-by time of the mobile station. For this reason in some mobile stations attempts have been made to circumvent this problem by e.g. turning power off from the display. On the other hand, in this case it is impossible to show the user useful information, like strength of field or battery status, by using the display. To circumvent this problem, Panasonic's Pinocchio PHS mobile station in fact carries two displays, a larger display for using e.g. to read and write text, when the mobile station is in use, and a small display to show status information when the mobile station is in standby mode. However, this solution is space-consuming and more expensive and slower to assemble than a single-display solution due to installation of separate components. One other problem caused by displaying the status information is the marks left on the display by years of displaying same data on same place, which marks can interfere with reading the text on the display.